Generally, various shapes of vessels have been produced in order to transport liquid cargo by sea. For example, a hull is designed depending on the characteristics of goods to be transported, for example, liquid cargo such as LNG (liquefied natural gas), LPG (liquefied petroleum gas), crude oil and the like and specific types of a cargo tank are applied to seal and store the goods of a hull under low temperature or high pressure conditions.
In manufacturing such hulls and cargo tanks, one of the main loading conditions is a sloshing problem. Sloshing is large liquid movement created by highly strong impact pressure on the inner walls of a storage space (that is, cargo tank) due to violent motion of liquid cargo having a free surface when the liquid cargo receives continuously the kinetic energy caused by the motion of a hull. Therefore, the sloshing problem is considered from the beginning of production of hulls and cargo tanks.
Thus, shapes of hulls and cargo tanks have been designed to minimize sloshing problem of liquid cargo and at the same time enough to withstand expected sloshing loads. In this process, a ship owner has to settle for a conditional operation restriction limiting loadage of a cargo to avoid structurally unbearable sloshing loads. Nevertheless, many problems of unexpected damage to the cargo tank have continuously occurred due to uncertainty of sloshing loads.
Such sloshing problems are the challenge to be solved in fuel tanks of space, aircraft and car industries as well as cargo tanks of ships. Because unlike ships, it is more important to supply fuel smoothly than to reinforce structure of a fuel tank in spaceship or airplane due to rapid fluid motion caused by sudden motions of the fuel tank such as a 360° rotation, sloshing problems have been resolved by controlling the motion of liquid cargo, for example liquid fuel.